You can get a DC Boost converter that will boost your 3.7 LiPoly to 5v. Of course, the boosted voltage will proportionally drop your effective battery life. (I haven’t used this product and I don’t know the seller, but it might work for you.)
The linked booster is rated for 3A, which is enough for the Norns shield. (Most USB power banks for phones have a 2.4A USB outlet for fast charging that seems to be enough.) It might get warm, so definitely make sure the case has enough ventilation.
Theoretically, if you want to include the battery, charger, and step-up converter in one case, it could work if the charger has a 3.7v out to the Pi so you never have to disconnect the battery. Then your power cable would connect to the input of the charger instead of the Pi, and the Pi would always be running off the battery. This will only work if the charger allows you to draw power from the battery while it’s charging.
Of note – the Micro USB is kind of the only simple way to get power to the RPi because the shield’s headers block the necessary GPIO pins for the 5v rail. You could hack that by soldering to headers on the bottom of the Pi. If you do that, I’d just add some hot glue to the joints to protect them from shorts, and provide some strain relief.
All that said, it’s totally possible and I’ll likely be doing something similar with an orbtronic battery – the 2500mAh battery fits exactly in the little gap next to the Pi and under the shield.
Feel free to DM me with questions if you want!
